[HBQRP] Another Project

[Piatt, Darwin]

OK, that’s what I get for ‘surfin’ the net while I had some spare time.
Guess what? Found another thing I think might make a fun project. Cost $15.00
Follow the URL

→ http://www.njqrp.org/sqm/index.html 

Just how good is that signal produced by your new DDS VFO?"  This is a common question with a difficult answer for anyone but those having a spectrum analyzer or other expensive lab equipment.
The Signal Quality Meter, or ‘SQM’, is an inexpensive and user-friendly device that produces a graphical display of relative quality of an RF signal applied to its input. Using a modern analog integrated circuit and other familiar RF components, the SQM examines an input RF signal and identifies how much unwanted harmonic or other off-frequency components are attenuated.  It provides a simple and easy way to determine how “clean” the output of an oscillator, amplifier or properly attenuated transmitter really is. 
Just connect your DDS or VFO signal to the SQM, adjust the control to notch out the fundamental frequency (say 7.040 MHz), and the resultant display of LED segments indicates how much "total harmonic energy" is remaining in the signal.  The fewer LEDs turned on, the better, indicating a low amount of cumulative extra signal components above the fundamental being measured.
Comments?

Darwin W.  Piatt Jr. (Dar) W9HZC
Midwest HomeBrewer’s and QRP Group
Polar Bear #9 - QCWA # 31632 
Flying Pigs # 936 - Zombie #826
GQRP – Iowa QRP Group
10-10 Webmaster (#73090)